The present invention relates to an apparatus for imparting good coherency characteristic to a running multifilament yarn by applying jet streams of a fluid thereto, so that yarn-constituting individual-filaments, are interlaced with one another. More particularly, the invention relates to a fluid treatment apparatus by which an improved coherence can be effectively imparted to a running multifilament yarn by utilizing a reduced quantity of a jetting fluid.
A method for the interlacing treatment by means of jetting a fluid to a running multifilament yarn is known as disclosed in the specifications of U.S. Pat. Nos. 2,985,995, 3,110,151 and 3,167,847. As a result of intensive research conducted on this known method, it was found that jet streams do not always promote interlacing of individual filaments of the yarn, but provide an interlacing effect only for a limited time under certain conditions. Thus, it has been confirmed that the working efficiency of this conventional method is very poor.